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Marine plastic pollution is projected to increase globally in the next few decades. This holds true for South America where the number of species that interacts with plastics is increasing. In this study, we explore for the first time the potential of certain charismatic species of marine turtles, mammals and seabirds as indicators of plastic pollution in the Río de la Plata (RdP), one of the largest and most important estuarine areas of the Southwest Atlantic. Through a revision of published studies integrated with unpublished data, we summarize studies on the interaction of charismatic marine species with plastics in the region and evaluate their role as indicators of plastic pollution in the RdP based on aspects of their local ecology and key attributes (i.e., biological/ecological, methodological, and conservation attributes) of indicator species. We found that at least 45 charismatic marine species interact –whether by ingestion or entanglement– with plastics in the region. Eight of these species were selected as potential indicators given their occurrence, probability of sampling and interaction with plastics in the RdP, namely: Chelonia mydas, Caretta caretta, Dermochelys coriacea, Pontoporia blainvillei, Arctocephalus australis, Otaria flavescens, Larus dominicanus, and Spheniscus magellanicus. The species shared some key attributes of indicator species, e.g., they are relatively well studied, but differed in critical aspects such as their home range and mobility. We discuss whether the species’ attributes are strengths or weaknesses according to the available knowledge on their ecology in the RdP, and propose a multispecies indicator of plastic pollution given that those strengths and weaknesses can be compensated among species. Monitoring plastic pollution through a combination of species would enable a better understanding of plastic pollution in this relevant area.

White croaker (Micropogonias furnieri) is the most important commercial fish of Rio de la Plata Estuary System (RLPES), one of the most extensive on the Southwest Atlantic coast. This paper describes the occurrence, abundance, and type of plastic debris (PD) present on the digestive tracts of 65 white croakers in the RLPES. Eighty percent of analyzed individuals had ingested PD, 156 of which (FO = 83.9%) were thread-like plastics and 30 were fragments (FO = 16.1%). The average number of pieces per digestive tract was 2.83 ± 3.14. Microplastic represented 85% of PD, most of them were < 2 mm and the prominent color was blue. Our results demonstrate the high occurrence of meso and microplastics in one of the most important species from an ecological and commercial viewpoint in the RLPES. The RLPES is the area of the Southwest Atlantic Ocean that concentrates most of the records of plastic waste in the environment, where the white croaker is the main commercial fish. In addition, M. furnieri is a main prey for several predators in the area. Although preliminary, this is a relevant contribution to the knowledge of marine debris pollution and its impact on the marine community of the region.

Male-only hauling grounds occur in close association to breeding colonies in several otariids. The occasional use of human-built infrastructure by these groups is also common. We observed permanent male aggregations of southern sea lions, Otaria flavescens, in urban contexts, such as two of the main fishing harbors in Argentina and investigated how they changed over 35 years. These haul-outs are located approximately 700 km from Uruguayan and northern Patagonian breeding grounds. Males in urban colonies have functional connections with both populations. A predictable pattern of dispersion during the breeding season, returning for winter, indicate site fidelity. Harbor habitats present ever changing stimuli, threats and challenges to habituated sea lions. Sequential, rapid and spontaneous changes in the location of the aggregations may be a response to quick learning and socially transmitted knowledge. Food provision via consumption of fish offal—complemented with natural foraging—provide support to these aggregations over prolonged periods. The presence of hundreds of sea lions in harbors represents a management challenge. Fidelity to resting areas and rapid habituation to human presence makes it difficult to design strategies that can deter sea lions from intensive use of critical sectors of port activity. Interaction with fishing gear results in frequent entanglements. The risk of transmission of diseases from and to dogs and other domestic animals is a major potential problem for individuals in unnatural aggregations.

In the last decades, an increasing fishing effort and a decreasing trend in fish catches have been observed in southern Brazil. Considering that marine mammals and fisheries usually compete for the same resources, it is reasonable to presume that the feeding ecology of these predators is affected by the current scenario. To evaluate this hypothesis, long-term variation in the diet of the South American sea lion (Otaria flavescens) relative to fisheries exploitation was analyzed for two periods (1993–2003 versus 2004–2014). The degree of overlap between the relative biomass of the sea lions’ diet and the target species of six types of local fishery was analyzed. An increase in prey overlap between sea lions and fisheries was observed in the more recent sampling period, along with an increase in prey diversity, richness, and niche breadth of the sea lions’ diet. These results suggest that the overfishing scenario could partly explain the modified feeding ecology of the sea lions. In this context, we recommend a review and better regulation of the current fishing effort in the region, which we believe will be an important step to maintain the fish stocks and minimize the impact of fishing on marine top predators. Fil: Machado, Rodrigo. Universidade Federal do Rio Grande do Sul; Brasil Fil: Rosa de Oliveira, Larissa. Universidade Do Vale Do Rio Dos Sinos; ; Brasil Fil: Ott, Paulo Henrique. Universidade Estadual Do Rio Grande Do Sul; ; Brasil Fil: Denuncio, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Haimovici, Manuel. Universidade Federal do Rio Grande do Sul; Brasil Fil: Cardoso, Luis Gustavo. Universidade Federal do Rio Grande do Sul; Brasil Fil: Danilewicz, Daniel. Universidade Estadual de Santa Cruz; Brasil Fil: Moreno, Ignacio Benites. Universidade Federal do Rio Grande do Sul; Brasil Fil: Borges-Martins, Márcio. Universidade Federal do Rio Grande do Sul; Brasil

Knowledge of growth patterns of an animal species is fundamental to understand their life history. This information is also used to help define population boundaries of threatened cetaceans, such as the Franciscana dolphin, Pontoporia blainvillei. A total of 108 Franciscana dolphins incidentally captured in artisanal fishing nets in estuarine and marine coastal waters of the northern part of the Franciscana Management Area IV (North FMA IV), Argentina, were studied. The objective of the present paper was to study age and growth parameters of Franciscanas from North FMA IV and to compare these parameters between estuarine and marine potential populations within this area. We used von Bertalanffy and Gompertz growth curves to model growth trajectories. The estimated asymptotic lengths demonstrated that Franciscana dolphins from this area were smaller (females: 136.3 cm and males, 122.1 cm) than southern FMA IV values previously published. They also showed the reverse sexual size dimorphism that is known across their range. However, the estimated asymptotic length was not statistically different between the estuarine and marine females within the study area. In spite of this, the fact that the northern forms of the FMA IV were smaller than the southern specimens supports the hypothesis of more than one population of the species within this management area. The North FMA IV has the highest reported mortality levels of Franciscana dolphins within the FMA IV; these results are relevant to the knowledge base of Franciscana dolphins in the region. Fil: Denuncio, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Negri, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Bastida, Ricardo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Rodriguez, Diego Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

The franciscana (Pontoporia blainvillei) is the most threatened small cetacean of South America. The species is endemic to coastal waters of the western South Atlantic Ocean, where it is distributed from Itaúnas (Brazil) to Golfo San Matias (Argentina). Its range was divided in four Franciscana Management Areas (FMAs) for conservation purposes. However, the distribution of the franciscana is not continuous along its range, with two hiatuses proposed in southeastern Brazilian coast. The absence of franciscana records in these regions has been confirmed by multiple years of research, however the reasons for this discontinuous distribution is not well understood. In this study, information on the distribution of the franciscana in south and southeastern Brazil is updated and new limits for FMAs are proposed. NicheA 3.0 software was used to investigate the environmental suitability of distributional gaps in relation to four weakly correlated, allegedly relevant descriptors of franciscana´s distribution. In total, 788 records from dedicated aerial and boat surveys and bycatch were used to verify and to confirm the new FMAs limits proposed by franciscana´s experts previously. The distributional gaps were reshaped and defined as following: Gap I from Piraquê-Açu River Mouth, Santa Cruz (19°57′S) in the state of Espírito Santo to Barra de Itabapoana (21°18′S) in the state of Rio de Janeiro; and Gap II from Armação dos Búzios (22°44′S) to Piraquara de Dentro (22°59′S) in Rio de Janeiro. The ecological niche model indicated that distributional gaps are inside franciscana´s fundamental niche, and are relatively suitable in terms of salinity, temperature, diffuse attenuation and bathymetry. However, the narrow of continental shelf seems to be the main factor explaining the absence of franciscanas in the distributional gaps as well as for the differentiation of some of the FMAs proposed. Narrowness of continental shelf seems to be intensifying the dynamics of biotic interactions promoting food competition for example, and/or causing geographic limitation to maintain minimal viable population size in present or past times periods. Fil: do Amaral, Karina Bohrer. Laboratório de Sistemática e Ecologia de Aves e Mamíferos Marinhos, Universidade Federal do Rio Grande do Sul; Brasil Fil: Danilewicz, Daniel. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul ; Brasil Fil: Zerbini, Alexandre. Instituto Aqualie; Brasil Fil: Di Beneditto, Ana Paula. Universidade Estadual do Norte Fluminense, Laboratório de Ciências Ambientais; Brasil Fil: Andriolo, Artur. Instituto Aqualie; Brasil Fil: Alvares, Diego Janisch. Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Animal, Instituto de Biociências; Brasil Fil: Secchi, Eduardo Resende. Universidade Federal do Rio Grande, Instituto de Oceanografia, Laboratório de Ecologia e Conservação da Megafauna Marinha-EcoMega; Brasil Fil: Ferreira, Emanuel. Entrada do Parque Estadual do Rio Vermelho - Associação R3 Animal, Rodovia João Gualberto Soares; Brasil Fil: Sucunza, Federico. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil Fil: Borges Martins, Márcio. Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Animal, Instituto de Biociências; Brasil Fil: de Oliveira Santos, Marcos César. Universidade de São Paulo, Departamento de Oceanografia Biológica, Instituto Oceanográfico, Laboratório de Biologia da Conservação de Mamíferos Aquáticos; Brasil Fil: Cremer, Marta. Universidade da Região de Joinville, Projeto Toninhas; Brasil Fil: Denuncio, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Ott, Paulo Henrique. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil Fil: Moreno, Ignacio Benites. Universidade Federal do Rio Grande do Sul, Laboratório de Sistemática e Ecologia de Aves e Mamíferos Marinhos; Brasil

In this paper, we examined the ingestion of marine debris (MD) in South American fur seals (SAFS), Arctocephalus australis, found dead in coastal beaches of northern Argentina and southern Brazil. Seven percent of 133 SAFS analyzed presented marine debris in their stomach (n = 10), with no differences between sampling countries (Brazil n = 7, Argentina n = 3) and sexes (female = 3; male = 6). However, significant differences were observed between ages classes, with MD exclusively present in stomach contents of young specimens. Plastics represents 90% of MD ingested by the SAFS, whereas regarding the source, fishery-related items (e.g. monofilament lines) were the main MD (70%), with a lesser proportion of packaging (e.g. pieces of bags). Low numbers but large size pieces of MD were found in each stomach affected. Negative effects on the individuals could not be fully evaluated. Therefore, the potential impacts of the marine debris to the SAFS deserve further elucidation. Fil: Denuncio, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Mandiola, María Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Pérez Salles, Sofía Belén. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Machado, Rodrigo. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Universidade Federal do Rio Grande do Sul; Brasil. Universidade do Estado de Santa Catarina; Brasil Fil: Ott, Paulo H.. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Universidade Estadual do Rio Grande do Sul; Brasil Fil: Rosa de Oliveira, Larissa. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Universidade do Vale do Rio dos Sinos; Brasil Fil: Rodriguez, Diego Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; Argentina

Fil: Denuncio, Pablo Ezequiel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Franciscana dolphin is an endemic cetacean in the southwestern Atlantic Ocean and is classified as Vulnerable A3d by the International Union for Conservation of Nature. Cadmium accumulation was assessed in two geographic groups from Argentina; one inhabits the La Plata River estuary, a high anthropogenic impacted environment, and the other is distributed in marine coastal, with negligible pollution. Despite the environment, marine dolphins showed an increase of renal Cd concentrations since trophic independence; while in estuarine dolphins was from 6 years. This is associated with dietary Argentine anchovy which was absent in the diet of estuarine dolphins, being a trophic vector of cadmium in shelf waters of Argentina. Cluster analysis also showed high levels of cd in association with the presence of anchovy in the stomach. The difference in the fine scale distribution of species influences dietary exposure to Cd and, along with other data, indicates two stocks in Argentina. Fil: Polizzi, Paula Sabrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Chiodi Boudet, Leila Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Romero, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Denuncio, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Rodriguez, Diego Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Gerpe, Marcela Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

El presente estudio describe la estructura de las asociaciones de poliquetos bentónicos del extremo sur de la Bahía de Samborombón, y su relación con los sedimentos, dos décadas después del último estudio realizado en la zona. Se establecieron tres estaciones de muestreo: Punta Rasa, Tapera de López y Arroyo San Clemente. En las mismas fueron identificadas cuatro especies de poliquetos: Laeonereis culveri, Heteromastus similis, Alitta succinea y Polydora cornuta, de las cuales L. culveri y H. similis resultaron las más abundantes. Se detectaron variaciones estacionales en la asociación y la abundancia de poliquetos en relación a la granulometría del sedimento. Punta Rasa y Tapera de López estuvieron caracterizadas casi exclusivamente por arena fina; allí se observaron las cuatro especies de poliquetos, siendo H. similis el dominante. En el Arroyo San Clemente, el sedimento dominante fue la arena media, adquiriendo gran importancia las pelitas. Alitta succinea estuvo ausente y Laeonereis culveri fue dominante. Estos resultados sugieren que los parámetros sedimentarios influirían sobre la variación en la distribución de poliquetos y que dicha variación se puede presentar aun en una escala espacial pequeña. Tanto la riqueza específica de poliquetos como la densidad general (individuos/m2) por estación fueron menores a los valores anuales observados en los estudios efectuados en la década del noventa. Esto podría deberse a que el presente trabajo fue realizado a principio de otoño, luego de la concentración de aves playeras (primavera-verano), que depredan con intensidad a estos organismos bentónicos. Este tipo de estudios resultan importantes al tratarse de un ambiente potencialmente afectado por las actividades antrópicas que tienen lugar en la zona interna del estuario del Río de la Plata. The present work describes the structure of benthic polychaete association of the southermost part of Samborombón Bay and its relationship with sediment after two decades of the last study made in the same area. Three sampling stations were established: Punta Rasa, Tapera de López and Arroyo San Clemente. Four species of polychaetes were identified: Laeonereis culveri, Heteromastus similis, Alitta succinea and Polydora cornuta, being L. culveri and H. similis the most abundant. Variations between stations in terms of the association and relative abundances of polychaetes with granulometry of sediment were recognized. Punta Rasa and Tapera de López were characterized almost exclusively by fine sand, observing the four species of polychaetes with dominance of H. similis. In Arroyo San Clemente the dominant sediment was medium sand, with pelites becoming important; A. succinea was absent and L. culveri was dominant. This indicates that variation in the distribution of polychaetes would be strongly influenced by the sedimentary parameters, and that this variation can arise even at small spatial scale. Both, polychaete species richness and general density (individuals/m2) by station were lower than density annual values observed in studies in the ‘90s. This could be because this study was conducted in the early fall, after shorebirds concentration (spring-summer), that strongly fed of these benthic organisms. This kind of studies is important since it is an environment potentially affected by human activities, taking place mainly in the inner zone of the Río de la Plata estuary.

The present study provides information about prey species consumed by franciscana dolphin, Pontoporia blainvillei, from southern Buenos Aires coast in Argentina. We collected 66 franciscana dolphins between 2003 to 2011 incidentally entangled in the artisanal fishing nets. We analyzed the stomach contents and estimated prey size in order to evaluate size overlapping with fisheries. Although remains corresponded to 11 prey species, only two were important in the diet, the striped weakfish, Cynoscion guatucupa, and the squid, Loligo sanpaulensis. Almost all prey present in the diet are of commercial interest. The overlapping of target species and prey that are subject to overfishing could enhance the vulnerability of franciscana by reducing food availability. Fil: Paso Viola, María Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Denuncio, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Negri, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Rodriguez, Diego Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Bastida, Ricardo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Cappozzo, Humberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The franciscana dolphin (Pontoporia blainvillei) is a small coastal dolphin endemic to the south-western Atlantic ocean. Incidental captures in fishing gillnets is possibly the greatest conservation concern for this species, and occurs within most of its geographical distribution. The aim of this paper is to determine the biological parameters of franciscana dolphin bycaught from artisanal coastal fisheries of the southern Buenos Aires province, Argentina. Between 2003 and 2009, carcasses of 54 incidentally captured franciscanas were collected. The age, sexual and physical maturity and body condition of each specimen was determined. The sex ratio of the bycaught dolphins did not differ from parity and, consistent with other areas, juveniles younger than 4 yr old were captured in higher proportion (69%). In addition, 74% of the entangled animals were sexually immature and 85% physically immature. Sexually immature dolphins were predominant in the spring, a period which coincides with the breeding season. An assessment of the body condition of captured franciscanas suggests that entanglements were not associated with a disease or physiological disorder. The results presented here are important to assess the impact of artisanal fisheries on the population of franciscana dolphins in the southernmost area of its distribution. Fil: Negri, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Panebianco, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina Fil: Denuncio, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Paso Viola, María Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina Fil: Rodriguez, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Cappozzo, Humberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina

In Argentina, the franciscana dolphin is one of the most vulnerable cetaceans regularly entangled in coastal artisanal fishery nets. The aim of this paper is to estimate the species' incidental mortality on the Southern coast of Buenos Aires province through interviews with the captains of artisanal fishing vessels, in the period 2006-2009. Franciscana bycatch was reported for gillnets and shrimper gear all year round but it occurred more frequently between October and February, at 5 km offshore and 10-20 m depth. The estimated mean annual incidental mortality was 107 dolphins (CI 95% = 87-129), 92 caught in gillnets (CI 95% = 73-112) and 15 in shrimpers' gear (CI 95% = 8-25) with a capture per unit effort of 0.029 dolphins per km of gillnet (CI 95% = 0.023-0.036) and 0.022 per shrimpe r's net (CI 95% = 0.012-0.035). Annual fluctuations were due to differences in the number of gillnetting fishing days. If mortality estimates for the Northern coast are also taken into account, values attain a maximum of 360-539 dolphins bycaught in the entire Buenos Aires province, representing 2.5-3.7% of the species' abundance in Argentina. This will inevitably lead to the decline of franciscana dolphin populations in the near future unless alternative fishing grounds are identified and alternative gearadopted.Na Argentina, a toninha é um dos cetáceos mais vulneráveis devido às capturas por rede de pesca artesanal. O presente estudo teve como objetivo estimar as capturas acidentais no sul da província de Buenos Aires, através de entrevistas aos capitães de barcos de pesca artesanal, entre os anos 2006-2009. As capturas foram reportadas para redes de emalhe e de camarão; com as mais altas frequências entre outubro e fevereiro, a 5 km da costa e 10-20 m de profundidade. A mortalidade acidental média anual estimada foi de 107 golfinhos (IC 95% = 87-129), 92 em redes de emalhe (IC 95% = 73-112) e 15 em redes de camarão (IC 95% = 8-25), com uma captura de 0,029 golfinhos/km de rede de emalhe (IC 95% = 0,023-0,036) e 0,024/rede de camarão (IC 95% = 0,012-0,035). As flutuações anuais responderam principalmente às diferenças nos dias de pesca. Considerando o último levantamento estimativo feito para o norte costeiro da província, estima-se uma mortalidade entre 360-539 golfinhos/ano em toda a província de Buenos Aires. Esses valores correspondem de 2,5-3,7% da abundância populacional da Argentina; o que traria como consequência um declínio populacional da espécie, tornando-se fundamental encontrar alternativas de pesca para a área.

Plastic debris (PD) ingestion was examined in 106 Franciscana dolphins (Pontoporia blainvillei) incidentally captured in artisanal fisheries of the northern coast of Argentina. Twenty-eight percent of the dolphins presented PD in their stomach, but no ulcerations or obstructions were recorded in the digestive tracts. PD ingestion was more frequent in estuarine (34.6%) than in marine (19.2%) environments, but the type of debris was similar. Packaging debris (cellophane, bags, and bands) was found in 64.3% of the dolphins, with a lesser proportion (35.7%) ingesting fishery gear fragments (monofilament lines, ropes, and nets) or of unknown sources (25.0%). PD ingestion correlated with ontogenetic changes in feeding regimes, reaching maximum values in recently weaned dolphins. Because a simultaneous increase in gillnet entanglement and the bioaccumulation of heavy metals take place at this stage, the first months after trophic independence should be considered as a key phase for the conservation of Franciscana dolphin stocks in northern Argentina.